BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)

BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X) (http://www.m3forum.net/m3forum/index.php)
-   E46 M3 (2001-2006) (http://www.m3forum.net/m3forum/forumdisplay.php?f=9)
-   -   M3 SMG pump reconditioning (http://www.m3forum.net/m3forum/showthread.php?t=413137)

SteveEvans Fri, Jul-06-2012 09:30:50 PM

M3 SMG pump reconditioning
 
5 Attachment(s)
My SMG gearbox light comes on occasionally, INPA reporting that the pump has been on too long. I've replaced the salmon pink relay but that's had no effect.

After one such incident, with INPA hooked up to the car I reset the errors and then repeatedly changed from 1st to 2nd and back again, watching the hydraulic pressure drop from ~75bar to ~50bar over the course of about 6 gear changes, and then saw it rise again taking about six seconds, hearing the pump run at the same time. Having done this several times the pressure failed to rise, the pressure instead staying at ~50bar. The pressure didn't so much as twitch, and I didn't hear the motor running. After a little while (~15 seconds, but I wasn't timing it) the gearbox warning light came on again reporting the normal fault. A few seconds later the pressure then rose, taking the normal six seconds to reach ~75bar.

The conclusion here is that the motor driving the pump wasn't working properly.

I've obtained a failed SMG pump unit from my local BMW specialist, and I've been stripping it down to refurb it as a replacement for my failing unit.

I didn't take photos of the motor removal (I'll take some when I replace it), but see below for the state of the motor commutator.

http://www.m3forum.net/m3forum/attac...1&d=1341609202

That is now being rewound, with the commutator, brushes and bearings being replaced for <150 (I'll post the precise price when I get it back). In the meantime, I thought I should check that the pump itself is OK.

The cover (which serves as a sump for the hydraulic fluid) needs to be removed.

http://www.m3forum.net/m3forum/attac...1&d=1341609202

Unscrew the pressure accumulator first, then remove the six torx bolts holding the cover on. The cover has a rubber 'o' ring style seal which should come away without any issue and can be reused.

This will reveal the pump with it's inlet filter in place.

http://www.m3forum.net/m3forum/attac...1&d=1341609656

This simply pulls off. Note that in the photo below I'd already removed the two torx bolts holding the pump in place.

http://www.m3forum.net/m3forum/attac...1&d=1341609656

Removing the two hex bolts to reveal the innards reveals the pump to be a roots style pump.

http://www.m3forum.net/m3forum/attac...1&d=1341609656

This was in perfect condition, so I've replaced it, and cleaned up the pump assembly, and I'm awaiting the return of the motor, very optimistic that it is the cause of the SMG unit failure.

I'll get my local BMW specialist to actually swap out my SMG unit with this one, which I suspect will be suffering from exactly the same fault.

More photos of the motor etc to come...

Steve

RedM3/4 Sat, Jul-07-2012 12:25:38 AM

Re: M3 SMG pump reconditioning
 
I've wondered about this for some time, nice job! I never pulled the motor apart, have pulled the pump apart, tested all solenoids, etc.
I will say if you go to pull the gear pump apart, witness mark everything, and be careful the gears don't just fall out. they appear symmetrical, but these things wear into each other, the steel gear to the brass bushing/bearing it rides in, so if you put it in upside down, it will look fine, but will create extra bearing wear that won't help longevity of the pump. Also be careful of the uniquely shaped rubber seals you see around the gears. They can tend to stick to one/both sides: if you rip one, I doubt you'd ever find a replacement, and at 1200 psi, hoping a torn one will seal ok is folly.
The pump I dis-assembled looked even better than this one, less discoloration of the gears/oil. It was fine, as the owner replaced it with a new one and that didn't solve the problem.
Honestly I think the whole unit runs way to hot: a bad symbiotic relationship between a motor that runs hot and a gear pump that eventually runs hot.

ADS

RedM3/4 Mon, Jul-09-2012 02:02:51 AM

Re: M3 SMG pump reconditioning
 
Actually, a properly designed hydraulic system should go millions of cycles of uninterrupted use. I think the temps are a factor, especially for the electric motor, so excited about how this goes.
If this works, also probably we could investigate and spec a replacement 12v motor and have very little downtime, although I like the value and ability to have a local shop repair the motor where possible.

ADS

Quote:

Originally Posted by Simann (Post 1065614550)
Thinking about how many thousands upon thousands of shifts per year the SMG system has to deal with, I would say this is purely wear and tear. Of course the easy and most costly way of repairing is always replacing with new...but if you can fix the unit for $300 USD and be out of a car for 2 weeks at most....that's a deal!


RedM3/4 Tue, Jul-10-2012 01:44:39 AM

Re: M3 SMG pump reconditioning
 
Maybe,
but probably added cost, plus question over controller running under the hood (temp range) or mounting it somewhere cooler. Would solve the brush problem and might run cooler though.

ADS

Quote:

Originally Posted by SliM3 (Post 1065616755)
It would be nice if we could find a suitable brushless motor replacement.


RedM3/4 Tue, Jul-10-2012 03:42:01 PM

Re: M3 SMG pump reconditioning
 
Curious, did your motor shop tell you the rewind was necessary from an armature test? Brushes and commutator cleanup would be relatively quick and inexpensive, but if the armatures are burning up, that will be more costly. And it probably says a lot about the severity of use/temp or call into question the duty cycle sizing.

ADS

SteveEvans Sat, Jul-14-2012 10:23:14 AM

Re: M3 SMG pump reconditioning
 
For the cost involved, once I saw the state of the commutator I just asked them to replace everything; windings, commutator, brushes, bearings, seals. Unfortunately they lost the end seal! It's only a dust seal, so a bead of silicone sealant will be OK, but rather annoying. I hope to receive the motor back on Monday.

Including VAT and shipping this has cost 183, so I hope it proves worthwhile. I've also got a replacement temperature sensor (p/n 13-62-1-709-966) from BMW for 26.

Steve

SteveEvans Sat, Jul-14-2012 10:32:28 AM

Re: M3 SMG pump reconditioning
 
Quote:

Originally Posted by SliM3 (Post 1065616755)
It would be nice if we could find a suitable brushless motor replacement.

I fly radio controlled helicopters for a hobby where brushless motors are the norm, so this thought did cross my mind. Considering that the SMG pump pulls ~20A at 12V, ie 240W, you get easily get a motor of double the power that's tiny. Below is an Align 450MX rated at 500W continuous, 750W peak.

http://www.align.com.tw/shop/images/...hml45m01_3.jpg

Unfortunately at 12V, this motors runs at 41000RPM, so a gearbox would be required. An awkward complication, and itself then prone to failure!

Steve

SteveEvans Sat, Jul-14-2012 10:45:21 AM

Re: M3 SMG pump reconditioning
 
Sorry for the quickfire posting, but I just found THIS reporting that BMW have issued a recall on M5/M6 models due to SMG motor failure. For the M5 you can buy the motor for the SMG pump for $330; see HERE. That's less than this rewind has cost me!

Heckafunctional Sat, Jul-14-2012 10:55:02 AM

Re: M3 SMG pump reconditioning
 
Quote:

Originally Posted by SteveEvans (Post 1065626021)
Sorry for the quickfire posting, but I just found THIS reporting that BMW have issued a recall on M5/M6 models due to SMG motor failure. For the M5 you can buy the motor for the SMG pump for $330; see HERE. That's less than this rewind has cost me!

Will the m5 motor fit on the e46 m3 trans?

SteveEvans Sat, Jul-14-2012 11:31:32 AM

Re: M3 SMG pump reconditioning
 
Doesn't look anything like it unfortunately.

Steve


All times are GMT. The time now is 09:27:17 PM.

Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright 1999-2017 M3Forum.com